1. Field of the Invention
The invention relates to disinfecting and preservative compositions which are particularly suited as disinfectants and preservatives for aqueous systems including those used in air conditioning, humidifying and cooling water systems.
2. The Prior Art
In hospital operating theaters, appropriate humidity must be maintained for reasons of safety. This can be achieved by steam humidification or circulation humidification. In circulation humidification, water in so-called "wash chambers" is circulated by pump and sprayed through fine nozzles. In order to prevent and combat transmission of infectious microorganisms by such air conditioning systems, the water employed must be treated so as to prevent the growth therein of microorganisms.
Although a number of antimicrobial additives for the wash chambers in humidification systems is known, they all suffer some kind of disadvantage and fail to meet certain important prerequisites so that the problem of preventing transmission of infectious microorganisms, which is so important in surgery, has not been satisfactorily resolved. The prerequisites a disinfecting and preserving agent for humidification systems should have are as follows:
1. broad spectrum of antimicrobial activity at low concentrations and low temperatures. PA0 2. stability against shearing forces and oxidation. PA0 3. low toxicity, especially inhalation toxicity. PA0 4. no undue foaming in use. PA0 5. essentially no odor.
Since foaming in systems where water is pumped and in air conditioning equipment, in whch foam particles may be carried into air conditioning ducts, is very troublesome, a disinfecting agent used in such systems should not cause foaming. Thus, the commonly employed quaternary ammonium compounds cannot be used because they cause heavy foaming.
Furthermore, the disinfecting agent used should have the lowest possible vapor pressure so that it will not evaporate from the aqueous system and reach room air. Therefore, well known disinfectants such as the lower aldehydes, e.g., formaldehyde, cannot be used.
Other well known disinfectants such as the higher alcohols and substituted phenols also cannot be used in air conditioning systems because they all have more or less pronounced odors.
Canadian Pat. No. 1,036,070 describes synergistic bactericidal compositions useful in surface disinfection, particularly surfaces soiled with organic matter, which comprises a 3-isothiazolone, a strong acid salt of a 3-isothiazolone, or a metal salt complex of a 3-isothiazolone and a bactericidal quaternary ammonium compound.
U.S. Pat. No. 3,870,795 describes certain 3-isothiazolones and metal salt complexes thereof and the use of solutions of the metal salt complexes as watercooling system microbiocides,
U.S. Pat. Nos. 3,517,022 and 3,870,795 describe certain benzoisothiazolones useful as microbiocides in aqueous systems.
U.S. Pat. Nos. 3,874,870 and 4,025,627 describe certain polymeric quaternary ammonium compounds which exhibit no undue foaming and are useful as microbiocidal agents in aqueous systems.
U.S. Pat. Nos. 3,931,319 and 4,027,020 describe certain polymeric quaternary ammonium compounds which are useful as microbiocidal agents.